Prevention of organ rejection in the clinic presently relies on administration of cocktails of immunosuppressants (Tacrolimus, Rapamycin, MMF, AZA, corticosteroids). The drugs are efficient for prevention of acute rejection, but do not prevent chronic rejection. In addition, because these drugs interfere with immune responses non-specifically, their chronic use exposes patients to high risks of cancer and infection. Other approaches that are being tested are co-stimulatory blockade and bone-marrow chimerism. However, “late-onset chronic rejection, as well as the toxicity of some of these regimens, remain as significant limitations that hamper clinical application” (Ochiai et al., Front. Biosci. 2007, 12:4248-53).